Hybrid vehicles may include a single ratio gear box or a step ratio automatic transmission. A controller of the hybrid vehicle typically selects a gear of the automatic transmission that is engaged and adjusts output of powertrain torque sources (e.g., internal combustion engine and/or electric machine) to improve vehicle efficiency. However, some human drivers prefer manual transmissions because manual transmissions allow the driver to have control over transmission gear shifting. To shift the manual transmission the driver depresses a clutch pedal and adjusts a position of a manual shift lever while the clutch pedal is depressed (e.g., applied). The clutch pedal opens a single clutch that disconnects an input shaft of the transmission from an engine crankshaft. Once the clutch is open, the driver may change a position of a shift lever to engage one of the transmission's gears. Once the gear is engaged, the clutch may be released to mechanically couple the engine's crankshaft to the vehicle's wheels. However, incorporating a manual transmission into a hybrid vehicle presents challenges. In particular, because the human driver is responsible for gear shifting, a gear shift may occur at nearly any time. A gear shift may disturb flow of power through the vehicle's powertrain and make it difficult or impracticable to carry on operation in a particular hybrid powertrain operating mode (e.g., series hybrid mode, parallel hybrid mode, electric vehicle only mode). Therefore, it may be desirable to provide a way of smoothly operating a hybrid vehicle that includes a manual transmission.
The inventor herein has recognized the above-mentioned disadvantages and has developed a method for operating a vehicle, comprising: operating a powertrain in an electric vehicle only drive mode; and starting combustion in an engine and adjusting engine rotational speed to a rotational speed of a transmission input shaft to exit the electric vehicle only drive mode in response to a human driver manually disengaging a clutch via a clutch pedal.
By starting an internal combustion engine and accelerating the engine to an input speed of a transmission input shaft, it may be possible to smoothly exit an electric vehicle only powertrain mode and enter a series or parallel hybrid powertrain operating mode. In particular, when the human driver depresses or applies a clutch pedal of a manual transmission while the vehicle is operating in an electric vehicle only hybrid powertrain operating mode, the internal combustion engine may be started (e.g., combusting fuel) so that engine torque may be available when the human driver releases the clutch pedal. If the human driver leaves the clutch pedal depressed while the engine is combusting fuel, then a battery may be charged to provide useful work from the engine. However, if the human driver released the clutch pedal and increases a driver demand torque, the engine power may be delivered to the vehicle's wheels. In this way, the human driver's operation of the clutch may be one of several conditions taken into consideration for switching between vehicle powertrain operating modes.
The present description may provide several advantages. In particular, the approach may allow a human driver to connect with a vehicle and provide smooth transitions between powertrain operating modes. Further, the approach may improve a human driver's confidence level when shifting a manual transmission. Additionally, the approach allows a human driver to change vehicle powertrain operating modes via a manual shift lever and operation of a clutch pedal.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.